@Override
public void clear() {
if (!isViewReady()) {
return;
}
if (!mDanmakuVisible || Thread.currentThread().getId() == mUiThreadId) {
mClearFlag = true;
postInvalidateCompat();
} else {
lockCanvasAndClear();
}
}
private void lockCanvas() {
if (mDanmakuVisible == false) {
return;
}
postInvalidateCompat(); // 设置 mRequestRender = true;
// --->invalidate触发onDraw(画完后mRequestRender = false; //复位
// 并unlockCanvasAndPost();)
// --->unlockCanvasAndPost中
// mDrawFinished = true; 标志画完
/* synchronized(obj) {
while(!condition) {
obj.wait();
}
obj.doSomething();
}
当线程A获得了obj锁后，发现条件condition不满足，无法继续下一处理，于是线程A就wait() , 放弃对象锁.
之后在另一线程B中，如果B更改了某些条件，使得线程A的condition条件满足了，就可以唤醒线程A：
synchronized(obj) {
condition = true;
obj.notify();
}*/
synchronized (mDrawMonitor) {
while ((!mDrawFinished) && (handler != null)) {
try {
mDrawMonitor.wait(200);
} catch (InterruptedException e) {
if (mDanmakuVisible == false || handler == null || handler.isStop()) {
break;
} else {
Thread.currentThread().interrupt();
}
}
}
mDrawFinished = false; // 复位
}
}